Porous containment device and associated method for stabilization of vertebral compression fractures

ABSTRACT

A porous containment device for implanting into the interior volume of a targeted vertebral body for use in restoring the anatomy of the targeted vertebral body. The porous containment device is expandable from an insertion configuration to an expanded configuration via, for example, a bone filler material. The porous containment device includes an enlarged proximal portion, an enlarged distal portion, and a narrower central portion located between the enlarged proximal and distal portions. The porous containment device includes at least one pore positioned between a midline of the narrower central portion and walls of the enlarged distal and proximal portions. The porous containment device may include one or more air or fluid evacuation pores to permit air or fluid to escape and internal or external constraints to form the narrower central portion. In addition, a cannulated sleeve may be used to insert the porous containment device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/743,293 filed May 17, 2010, which is a U.S. National PhaseApplication of International Application No. PCT/US2008/083350 filedNov. 13, 2008, which claims the benefit of U.S. Provisional ApplicationNo. 60/988,696, filed on Nov. 16, 2007, the contents of all priorapplications are hereby incorporated by reference in their entirety forall purposes.

FIELD OF THE INVENTION

The present invention relates generally to an implant for augmenting orsupporting bones or other structures such as, for example, a vertebralbody. More specifically, the present invention relates to a porous orpermeable containment device and associated methods and instrumentationfor the treatment of compressed bone voids, more specifically, vertebralcompression fractures.

BACKGROUND OF THE INVENTION

Vertebral compression fractures (“VCF”) represent a common spinal injuryand may result in prolonged disability. Generally speaking, VCF involvescollapsing of one or more vertebral bodies in the spine. VCF usuallyoccurs in the lower vertebrae of the thoracic spine or the uppervertebrae of the lumbar spine. VCF generally involves fracture of theanterior portion of the affected vertebral body. VCF may result indeformation of the normal alignment or curvature, e.g., lordosis, of thevertebral bodies in the affected area of the spine. VCF and/or relatedspinal deformities may result, for example, from metastatic diseases ofthe spine, from trauma or may be associated with osteoporosis. Untilrecently, doctors were limited in how they could treat VCF and relateddeformities.

Recently, minimally invasive surgical procedures for treating VCF havebeen developed. These procedures generally involve the use of a cannulaor other access tool inserted into the posterior of the targetedvertebral body, usually through the pedicles.

In one such procedure, a cannula or bone needle is passed through thesoft tissue of the patient's back. Once properly positioned, a smallamount of polymethylmethacrylate (PMMA) or other orthopedic bone cementis pushed through the needle into the targeted vertebral body. Thistechnique may be effective in the reduction or elimination of fracturepain, prevention of further collapse, and a return to mobility inpatients. However, this technique typically does not reposition thefractured bone into its original size and/or shape and, therefore, maynot address the problem of spinal deformity due to the fracture.

Other treatments for VCF generally involve two phases: (1) reposition orrestoration of the original height of the vertebral body and consequentlordotic correction of the spinal curvature; and (2) augmentation oraddition of material to support or strengthen the fractured or collapsedvertebral body.

One such treatment involves inserting, through a cannula, a catheterhaving an expandable member into an interior volume of a fracturedvertebral body, wherein the interior volume has a relatively softcancellous bone surrounded by fractured cortical bone therein. Theexpandable member is expanded within the interior volume in an attemptto restore the vertebral body towards its original height. Theexpandable member is removed from the interior volume, leaving a voidwithin the vertebral body. PMMA or other bone filler material isinjected through the cannula into the void to stabilize the vertebralbody. The cannula is then removed and the cement cures to augment, fillor fix the vertebral body.

Another approach for treating VCF involves inserting an expandable meshgraft balloon or containment device into the targeted vertebral body.The graft balloon remains inside the vertebral body after it is inflatedwith PMMA or an allograft product, which limits intra-operative loss ofheight of the repositioned endplates.

It is desirable in the art to provide a safe and effective porous orpermeable containment device and methods for aiding and/or augmentingfractured or otherwise damaged vertebral bodies and other bones,preferably a porous or permeable containment device that may be insertedvia a minimally invasive surgical technique and which prevents slippagebetween the containment device and the surrounding bone tissue.

SUMMARY OF THE INVENTION

The present invention is directed to a porous or permeable containmentdevice for implanting into an interior volume of a targeted vertebralbody for use in restoring the anatomy of the targeted vertebral body.The containment device is expandable from an insertion configuration toan expanded configuration via, for example, a bone filler material suchas, for example, a bone cement. Expansion of the containment device byinjection of the bone filler material preferably facilitates (i) cavitycreation within the interior volume of the targeted vertebral body, (ii)height restoration of the vertebral body, (iii) filling of the cavityformed in the interior volume of the targeted vertebral body, and (iv)stabilization, aiding and/or augmentation of the targeted vertebralbody. The porous or permeable containment device preferably enables (i)controlled bone cement outflow, (ii) increased contact surface with thesurrounding cancellous bone and (iii) stabilization of the rotationaland axial-translational movements of the porous containment device withrespect to the surrounding cancellous bone.

The containment device preferably permits the bone filler material toflow out of or through the outer surface of the containment device via,for example, one or more pores formed in the outer surface, one or moreflow-directing tentacles extending from the outer surface, by formingthe containment device from a permeable material, etc. so that the bonefiller material may interdigitate with the surrounding bone tissue. Thecontainment device is preferably configured to have a pre-determined,specific shape such as, for example, a “dog-bone” or “dumb-bell” shape,when in the expanded configuration, in order to enhance primarystabilization. The pores may also incorporate a specific shape andconfiguration to optimally meet the requirements of secreting the bonefiller material, tissue infiltration and anchorage of the containmentdevice to the surrounding bone tissue.

The containment device preferably also includes one or more knobs orribs to facilitate anchoring of the containment device to thesurrounding bone tissue, one or more air or fluid evacuation pores topermit air or fluid from escaping from the interior volume of thecontainment device, one or more radiopacity rings or markers to enable asurgeon to locate and/or position the containment device under X-rayimaging, and/or any of the other features disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe preferred embodiments of the application, will be better understoodwhen read in conjunction with the appended drawings. For the purposes ofillustrating the porous containment device of the present application,there is shown in the drawings preferred embodiments. It should beunderstood, however, that the application is not limited to the precisearrangements and instrumentalities shown. In the drawings:

FIG. 1A illustrates an exemplary embodiment of a containment deviceinserted into an interior volume of a targeted vertebral body, thecontainment device illustrated in an insertion configuration;

FIG. 1B illustrates the containment device shown in FIG. 1A in anexpanded configuration;

FIG. 2A illustrates a perspective view of an exemplary embodiment of acontainment device in accordance with one aspect of the presentinvention;

FIG. 2B illustrates a side view of the containment device shown in FIG.2A, the containment device illustrating different exemplary features notillustrated in FIG. 2A;

FIG. 3 illustrates an alternate perspective view of the containmentdevice shown in FIG. 2A, the containment device including secreted bonefiller material semi-contained between enlarged distal and proximalportions of the device in accordance with one aspect of the presentinvention;

FIG. 4 illustrates a side view of the containment device in an insertionconfiguration within the lumen of a cannula;

FIG. 5 illustrates a detailed, partial view of an alternate exemplaryembodiment of a containment device incorporating a plurality oftentacles extending from an outer surface of the containment device inaccordance with one aspect of the present invention;

FIG. 6A illustrates a detailed, partial view of the containment deviceshown in FIG. 5 being expanded by bone filler material;

FIG. 6B illustrates a detailed, partial view of the containment deviceshown in FIG. 5 being further expanded by bone filler material;

FIG. 6C illustrates a detailed, partial view of the containment deviceshown in FIG. 5 being further expanded by bone filler material;

FIG. 7 illustrates an alternate exemplary embodiment of a containmentdevice, the containment device including a plurality of knobs and ribsin accordance with one aspect of the present invention;

FIG. 8A illustrates an exemplary embodiment of a cement viscosityindicator in accordance with another aspect of the present invention;

FIG. 8B illustrates an alternate, exemplary embodiment of a cementviscosity indicator;

FIG. 9 illustrates a side view of an exemplary embodiment of acannulated sleeve used in connection with the porous containment deviceof the present invention;

FIG. 10A illustrates an exploded, perspective view of an exemplarycoupling mechanism for coupling the porous containment device to acannulated sleeve; and

FIG. 10B illustrates a perspective view of the porous containment devicecoupled to the cannulated sleeve device via the coupling mechanismillustrated in FIG. 10A.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “lower”, “upper”,“top” and “bottom” designate directions in the drawings to whichreference is made. The words “inwardly” and “outwardly” refer todirections toward and away from, respectively, the geometric center ofthe device and designated parts thereof. The words, “anterior”,“posterior”, “superior”, “inferior” and related words and/or phrasesdesignate preferred positions and orientations in the human body or withrespect to the implant of the present application to which reference ismade and are not meant to be limiting. The terminology includes theabove-listed words, derivatives thereof and words of similar import.

Certain exemplary embodiments will now be described with reference tothe drawings. In general, such embodiments relate to an implant forcreating a cavity within an interior volume of a vertebral body, forrestoring the height of the vertebral body, for filling the cavityformed in the vertebral body and for stabilizing, aiding and/oraugmenting the patient's vertebral body and spine. As generallyunderstood by one of ordinary skill in the art, it should be understoodthat while the preferred implant will be described as and may generallybe used in the spine (for example, in the lumbar, thoracic or cervicalregions), those skilled in the art will appreciate that the implant maybe used in other parts of the body such as, for example, long bones orbones in the hand, face, feet, extremities, cranium, or in nearly anybone in the human body.

Referring generally to FIGS. 1A-7, the present invention is generallydirected to a porous or permeable containment device 20 (collectivelyreferred to herein as a “porous containment device” and/or a“containment device”) and to a system and method for inserting theporous containment device 20 into a targeted vertebral body V of avertebra, such as, for example, one which has been subjected to a VCF.The porous containment device 20 is preferably sized and configured tobe inserted into an interior volume 2 of the targeted vertebral body Vvia a minimally invasive surgical technique, such as, for example,through one or more cannulas 100 (as best shown in FIG. 4), preformedholes or percutaneously. Once inserted into the interior volume 2 of thetargeted vertebral body V, the porous containment device 20 isexpandable from an insertion configuration (as best shown in FIGS. 1Aand 4) to an expanded configuration (as best shown in FIGS. 1B, 2A, 2B,3 and 7) so that the porous containment device 20 may generally create acavity within the interior volume 2 of the targeted vertebral body V,restore the height of the vertebral body V and stabilize, aid and/oraugment the interior volume 2 of the targeted vertebral body V.Preferably, the porous containment device 20 is capable of repositioningand stabilizing the targeted vertebral body V to re-establish structuralintegrity and avoid painful micro-movements.

The porous containment device 20 is preferably expanded from theinsertion configuration to the expanded configuration via a bone fillermaterial 50. The bone filler material 50 may be, for example, bonechips, allograft bone or any other filling material now or hereafterknown in the art. Preferably the bone filler material is a biocompatiblebone cement such as, for example, polymethylmethacrylate (PMMA) that isself hardening (e.g., self-curing) and that is capable ofinterdigitating with the surrounding bone tissue 4 found in the interiorvolume 2 of the targeted vertebral body V. In this manner, the fillingof the cavity formed in the vertebral body and the stabilization of thetargeted vertebral body V is accomplished by the injection of the bonefiller material 50, the expansion of the porous containment device 20and the controlled secretion of the bone filler material 50 out of orthrough the porous containment device 20, as will be described ingreater detail below.

In use, the porous containment device 20 is inserted preferably via aminimally invasively apparatus or system 100 into a targeted vertebralbody V. The porous containment device 20 is preferably then expandedfrom the insertion configuration to the expanded configuration viainjection of the bone filler material 50 into the inner cavity of theporous containment device 20 using an injection device. The expansion ofthe porous containment device 20 preferably compresses the surroundingcancellous bone tissue 4 in the interior volume 2 of the targetedvertebral body V thereby forming a cavity. Expansion of the porouscontainment device 20 also preferably repositions and stabilizes thesurrounding bone and/or bone tissue 4. That is, the porous containmentdevice 20, in the expanded configuration, is preferably structurallystrong enough to impart a force to the surrounding bone tissue 4 in theinterior volume 2 of the targeted vertebral body V sufficient to restorethe anatomical alignment of the fracture vertebral body V untilhardening of the injected bone filler material 50.

The outer surface of the porous containment device 20 is preferablyconfigured so that a small amount of bone filler material 50 issecreted, more preferably directionally secreted, out of or through theporous containment device 20. The relatively small amount of bone fillermaterial 50 may be secreted out of or through the porous containmentdevice 20 via one or more pores 35 formed in the containment device 20,by one or more tentacles 46 extending from the outer surface of thecontainment device 20, by forming the porous containment device 20 froma permeable material, etc. Once secreted, the bone filler material 50cures to form a cement layer 51 around the porous containment device 20that interdigitates with the surrounding bone tissue 4 (resulting in alayer of cement-bone compound 51). The porous containment device 20,once filled with the bone filler material 50, remains within theinterior volume 2 of the targeted vertebral body V to preferably assistin load bearing and structural support of the vertebral body V as thebone filler material 50 cures.

The porous containment device 20 may be configured so as to besemi-constrained or selectively reinforced. In this manner, the porouscontainment device 20 may be configured so that in the expandedconfiguration, the containment device 20 has a pre-determined size andshape. For example, the porous containment device 20 may be configuredto expand in one direction but not in another, e.g., preferably radiallyrather than in length. Alternatively or in addition, the porouscontainment device 20 may be configured to expand towards an area ofless resistance. The porous containment device 20 may be configured sothat in the expanded configuration, the device has, for example, acylindrical, conical, cigar-like, rounded, or other desired shape.

In a particularly preferred embodiment and as generally shown in FIGS.2A, 2B and 3, the porous containment device 20 may be in the form of anexpandable balloon that, when in the expanded configuration, has a“dog-bone” or “dumb-bell” type shape (collectively referred to herein asa “dog-bone”). That is, the porous containment device 20 includes aproximal portion 22 having an outer diameter D1, a distal portion 24having an outer diameter D2, and a central portion 26, located betweenthe proximal and distal portions 22, 24, having an outer diameter D3.The diameter D3 of the central portion 26 is less than the diameters D1and D2 of the proximal and distal portions 22, 24, respectively, thusforming the “dog-bone” shape. Diameter D1 may be equal to, larger thanor smaller than diameter D2. Moreover, it is envisioned that thenarrower diameter D3 can be located in the proximal or distal portions22, 24 of the porous containment device 20. Diameter D3 preferably isapproximately 5% to 60% of the diameter D1 and/or D2 to enable theenlarged diameter distal and proximal portions 22, 24 to act as a bufferand to allow for a pooling effect or to substantially semi-contain thesecreted bone filler material 50, as will be described in greater detailbelow. By providing enlarged distal and proximal end portions 22, 24,the containment device 20 facilitates better interdigitation with thesurrounding bone tissue 4. In addition, the containment device 20enables 360 degrees of secreted bone filler material 50 forinterdigitation with the surrounding bone tissue 4 (as best illustratedin FIG. 3).

It should be further noted that it is envisioned that the containmentdevice 20 may include a plurality of narrower portions. For example, thecontainment device 20 may include two narrower portions sandwichedbetween three enlarged diameter portions such that the containmentdevice 20 may have a double, “dog-bone” shape.

The “dog-bone” shaped porous containment device 20 may be made byincorporating one or more internal or external constraints such as, forexample, one or more wires, one or more metal radial rings or any formof supportive yarn 30 to constrain expansion of the narrower diametercentral portion 26.

As shown, the “dog-bone” shaped containment device 20 preferablyincludes a plurality of pores 35 formed in the narrower central portion26. In this manner, in use, the porous containment device 20 enablesoutflow of the bone filler material 50 through the plurality of pores 35formed in the narrower central portion 36 of the porous containmentdevice 20. In the expanded configuration, the enlarged diameter proximaland distal portions 22, 24 act as buffers so that the secreted bonefiller material 50 is substantially, semi-contained in the narrowercentral portion 26 and the secreted bone filler material 50 is therebypooled or semi-contained in a buffered zone between the enlargeddiameter distal and proximal portions 22, 24 (as best illustrated inFIG. 3). The secreted bone filler material 50 preferably forms a cementlayer 51 around the porous containment device 20 to facilitateinterdigitation of the containment device 20 with the surrounding bonetissue 4.

The plurality of pores 35 located in the narrower central portion 26 arepreferably oriented so that the outflow of bone cement 50 is directedcentrally and/or towards the base (e.g., towards the outer surface) ofthe narrower central portion 26. The enlarged distal and proximalportions 22, 24 will act as a buffering system limiting and/orpreventing anterior or posterior backflow or leakage.

In one embodiment, the one or more pores 35 may be initially coveredwith a material or closed by having a locally smaller thickness thanthat which characterizes the remainder of the porous containment device20. The pores 35 may include a predetermined breaking point such thatthe pores 35 rupture or open upon experiencing a certain predeterminedpressure.

The number of pores 35 and the diameter of the pores 35 are preferablyselected to optimize desired cement outflow. Preferably the “dog-bone”shaped porous containment device 20 includes between one and twentypores 35 depending on the size of the porous containment device 20.Although larger number of pores 35 may be incorporated. The pores 35 canbe positioned anywhere between the midline of the narrower centralportion 26 and the walls of the enlarged distal and proximal portions22, 24. The diameter of the pores 35 is preferably between about 50microns and about 1,000 microns and more preferably about 450 microns.

Alternatively and/or in addition, the porous containment device 20 mayinclude one or more surface enhancing structures 40 to improve thefrictional contact strength of the porous containment device 20 with thesurrounding bone tissue 4 found in the interior volume 2 of the targetedvertebral body V thereby helping to further anchor and to preventslippage of the porous containment device 20 within the targetedvertebral body V.

The surface enhancing structures 40 may be in the form of knobs 42 orribs 44. For example, the porous containment device 20 may include aplurality of axial or longitudinal ribs, radial or diametric ribs,C-shaped ribs, T-shaped ribs, etc. In addition to help facilitateanchoring the containment device 20 to the surrounding bone tissue 4,the surface enhancing structures 40 may also be positioned relative tothe plurality of pores 35 to help direct the outflow of the bone fillermaterial 50. That is, the surface enhancing structures 40 may be placedon or formed on the containment device 20 to help direct the outflow ofthe bone filler material 50. For example, one or more pores 35 may beplaced between adjacent ribs 44 so that any secreted bone fillermaterial 50 may be contained by the adjacent ribs 44. In addition, theplacement of the ribs 44 may be used to direct the flow of the bonefiller material 50 such as, for example, to direct the flow of the bonefiller material 50 so that it only flows in the anterior-posteriordirection, etc.

Alternatively and/or in addition, the porous containment device 20 mayinclude a plurality of projections (not shown) having, for example, adonut or red-blood cell shaped structure. That is, the porouscontainment device 20 may include a plurality of circular projectionswith a central hole wherein each projection surrounds a pore 35 so thatas the bone filler material 50 is secreted from the pore 35, thesecreted bone filler material 50 is substantially contained by andremains within the central hole formed in the donut shaped projection.

Alternatively and/or in addition, the surface enhancing structures 40may be in the form of tentacles 46 (as best shown in FIGS. 5-6C). Thatis, in order to facilitate primary fixation of the surrounding bonetissue 4 with the outer surface of the porous containment device 20, theouter surface of the porous containment device 20 may include aplurality of tentacles 46, which are projections extending from theouter surface of the porous containment device 20. The arrangement ofthe tentacles 46 can assume many different forms and may be tailored tothe requirements of the surgery and the specific anatomy of the patientand may, for example, be arranged homogenously or non-homogenously aboutthe outer surface of the porous containment device 20. Alternatively,the plurality of tentacles 46 may be arranged only on one or moresurfaces such as, for example, only on the superior and inferiorsurfaces, of the porous containment device 20 (e.g., the surfaces thatface the top and bottom interior endplates of the vertebral body) or onthe superior and inferior surfaces but unilaterally arranged.

Each of the plurality of tentacles 46 preferably includes one or moreopenings 48 at the outer end or tip thereof for directing the outflow ofthe bone filler material 50 to form a cement layer 51 around the porouscontainment device 20 to facilitate interdigitation of the containmentdevice 20 with the surrounding bone tissue 4 in the interior volume 2 ofthe targeted vertebral body V (as best shown in FIG. 6A). Alternatively,the one or more openings 48 may be formed at the foot of the tentacles46 (as best shown in FIG. 6B) or between the foot of the tentacles 46and the outer end or tip of the tentacles 48 (as best shown in FIG. 6C).Moreover, the one or more openings 48 may be formed along the length ofthe tentacles 46. In one embodiment, the one or more openings 48 mayinclude a predetermined breaking point such that the openings 48, whichmay be initially covered with a material or closed by having a locallysmaller thickness than that which characterizes the remainder of theporous containment device 20, ruptures upon experiencing a certainpredetermined pressure.

In addition, in some embodiments, the plurality of tentacles 46 may besufficiently rigid to assist in anchoring the porous containment device20 into and/or with the surrounding bone tissue 4 and to prevent shearforce delamination between the surrounding bone tissue 4, the bonefiller material 50 and the porous containment device 20.

In use, as the porous containment device 20 is expanded via injection ofthe bone filler material 50 into the inner cavity of the porouscontainment device 20, the plurality of tentacles 46 formed on the outersurface of the porous containment device 20 preferably extend and/orbecome adhered with the surrounding bone tissue 4. In addition, the oneor more openings 48 formed in the tentacles 46 preferably direct thebone filler material 50 to flow out of the porous containment device 20and into the surrounding bone tissue 4.

It should be noted that it is envisioned that the one or more surfaceenhancing structures 40 (e.g., the knobs 42, ribs 44 or tentacles 46)can be used in connection with any known or hereafter developedcontainment device including, for example, non-porous containmentdevices. For example, as best shown in FIG. 7, the containment device20′ may be in the form of a rounded or rectangular shaped containmentdevice. The containment device 20′ may be porous or non-porous. Thecontainment device 20′ including a plurality of knobs 42 and ribs 44 tofacilitate anchoring of the containment device 20′ to the surroundingbone tissue 4.

Alternatively or in addition, the porous containment 20 devicepreferably includes one or more air and fluid evacuation pores 60 toenable the bone filling material 50 and any blood or any fluid or airwithin the inner cavity of the porous containment device 20 to escape.Preferably the one or more air and fluid evacuation pores 60 have adiameter of about 1 micron to about 49 microns.

Alternatively or in addition, the porous containment device 20preferably includes one or more radiopacity rings or markers 65 toenable the surgeon to precisely locate and/or position the porouscontainment device 20 under X-ray imaging.

Preferably the bone filler material 50 is secreted from the porouscontainment device 20 at a pressure different from the injected pressurethat expands the porous containment device 20, as will be described ingreater detail below.

The size and the total surface area of the pores 35 and/or openings 48are preferably configured so that only a limited amount of viscous bonefiller material 50 can exit from the porous containment device 20 duringinitial injection of the bone filler material 50. As will be describedin greater detail below, initial injection of the bone filler material50 preferably occurs at a relatively low viscosity. As previouslystated, the pores 35 and/or openings 48 can be engineered to include apredetermined breaking point such as, for example, forming the pores 35and/or openings 48 with a locally thinner material thickness than thatof the rest of the porous containment device 20, so that the pores 35can rupture in response to reaching a predetermined pressure. Theinteraction between the viscosity of the bone filler material 50 (ratherhigh) and the geometry of the pores 35 and/or openings 48 (rather small)is coordinated to reach a balanced outcome fulfilling the requirementsof cavity creation, height restoration, and secretion of the bone fillermaterial 50 locally to infiltrate into the surrounding bone tissue 4.

Thus, in use, in order to facilitate a proper combination ofcement-tissue interdigitation with volume or height restoration, thebone filler material 50 may be injected into the porous containmentdevice 20 in a liquid or pasty form, and in a preferred embodiment, avolume of 1-5 cc of bone cement 50 is initially injected into the porouscontainment device 20 at a low viscosity to allow for controlledextravagation and interdigitation with the surrounding bone tissue 4.Thereafter, additional injection of 1-5 cc of bone cement 50 at arelatively higher viscosity will allow volume creation and thus heightrestoration and will further enhance the interdigitation of the secretedbone cement 50 with the surrounding bone tissue 4. Preferably the bonecement 50 is initially injected at a low viscosity of between about 30Pas to about 150 Pas. Thereafter, the bone cement 50 is injected at arelatively higher viscosity between about 300 Pas to about 2,000 Pas.

To facilitate bone cement 50 injection, the system preferablyincorporates a single use or multiple use cement viscosity indicator 150(as best shown in FIGS. 8A and 8B). During bone cement 50 injection, acorrect indication of the cement viscosity is important in order toguarantee safe and efficient void filling. Injection of a bone cement 50with too high of a viscosity or too low of a viscosity might result inbone cement leakage or inappropriate execution of a medical technique.Injection of a bone cement 50 with too high of a viscosity might alsoresult in inappropriate filling of the bone voids, damage to surroundingtissue, etc. Generally speaking however it is difficult for surgeons toknow the viscosity of the bone cement 50 at any given time in thesurgical operating room.

The cement viscosity indicator 150 includes a processor containing amathematical algorithm. Preferably, the cement viscosity indicator 150is a compact sterile electronic device allowing application directlywithin the surgical operating room thereby allowing accurate reading ofthe room temperature and thus determination of the bone cement viscosityin time.

In use, upon start up, the cement viscosity indicator 150 measures thecurrent room temperature and runs the temperature through the computeralgorithm. Once the algorithm determines that the bone cement 50 iswithin a predetermined acceptable viscosity, the cement viscosityindicator 150 informs the surgeon that the bone cement 50 is ready forinjection. In accordance with the preferred two-step injection method,as previously described, the cement viscosity indicator 150 preferablyindicates to the surgeon when the bone cement 50 has achieved the properlow viscosity for initial injection and when the bone cement 50 hasachieved the proper high viscosity for final injection.

The cement viscosity indicator 150 may function by registering one ormore points in time corresponding with a specific viscosity. This willallow application of bone cement 50 with the right viscosity at theright moment. Obtaining the right viscosity could be communicated underthe form of a visual and/or acoustic signal.

The porous containment device 20 preferably has a diameter of about 10mm to about 25 mm in height and a length of about 10 mm to about 25 mm,when in the expanded configuration. Although other larger or smallerdimensions may be used. The porous containment device 20 may be used asa stand-alone device or in combination with one or more othercontainment devices in the same interior volume 2 of the targetedvertebral body V such as, for example, in a transpedicular approach.

The porous containment device 20 may be in the form of a balloon. Theballoon may be made from any biocompatible material now or hereafterknown including but not limited to polycarbonate (PU), polycarbonateurethane (PCU), polyethylene terephthalate (PET), polyethylene (PE),thermoplastic polyamide (TPA), PEBAX, or other elastic and expandablepolymeric materials, or inelastic polymer materials. Alternatively, theporous containment device 20 can be in the form of a mesh. The mesh canbe made from any biocompatible now or hereafter known including but notlimited to polyetheretherketone (PEEK), polyethylene terephthalate(PET), polycarbonate (PU), etc. Alternatively, the porous containmentdevice 20 can be made from a resorbable material that is preferablynaturally resorbed by the human body over time. Forming the porouscontainment device 20 from a resorbable material is particular usefulwhen using a bone filler material 50 that is naturally replaced by boneover time. The porous containment device 20 can also be formed of apermeable membrane or a mesh-like material that allows the bone fillermaterial 50 to flow out of the outer surface of the containment device20 and into contact with the surrounding bone tissue 4, with or withoutthe inclusion of pores 35, tentacles 46, etc.

The porous containment device 20 is preferably pre-formed (e.g.,presized and shaped) when in the expanded configuration and is made of anon-elastic or semi-rigid material.

Alternatively or in addition, the porous containment device 20 may bereinforced by or used with a stent, a stent-like structure, a deformablemesh or reinforcing fibers, which may act as both an expansion deviceand a filler sack, in which most of the bone filler material 50 remainsafter injection but which permits some bone filler material 50 to escapethrough the stent or mesh to interdigitate with the surrounding bonetissue 4.

Alternatively or in addition, the porous containment device 20 may bemade from a material, which as a result of the rising temperature fromthe bone filler material 50 curing, undergoes a chemical reaction withthe bone cement 50 causing the porous containment device 20 to merge,fuse, melt, or cross-link with the bone cement 50.

Alternatively or in addition, the porous containment device 20 may bemade from a material, which as a result of the rising temperature fromthe bone filler material 50 curing, becomes liquid so that the meltedcontainment device flows into and interacts with the surrounding bonetissue 4. Alternatively, only a portion of the containment device 20 maybe configured to melt as a result of the rising temperature from thebone cement 50 curing, such as, for example, only the knobs 42, ribs 44or tentacles 46.

In an alternate embodiment (not shown), the porous containment devicemay include an outer containment device and an inner containment devicesuch that the outer containment device surrounds the inner containmentdevice. In use, the inner containment device is responsible for cavitycreation and for restoring the high of the vertebral endplates. Theouter containment device is responsible for enabling bone fillermaterial to interdigitate with the surrounding bone tissue. The innercontainment device may include a plurality of pores that are smaller indiameter or fewer in number than those formed in the outer containmentdevice. The inner containment device and the outer containment devicemay be simultaneously inserted into the targeted vertebral body in aninsertion configuration. Alternatively, the inner and outer containmentdevices may be inserted sequentially in separate steps.

In use, bone filler material is preferably injected into the innercontainment device to facilitate cavity creation and repositioning ofthe vertebral body without a large out-flow of bone filler material.Bone filler material preferably flows through the inner containmentdevice, more preferably through the pores formed in the innercontainment device, and into the area between the inner and outercontainment devices eventually resulting in the bone filler materialpassing through the outer containment device and into engagement withthe surrounding bone tissue. The inner containment device may beconfigured to permit the bone filler material to outflow only after apredetermined pressure or volume is achieved in the inner cavity of theinner porous containment device. The outer porous containment devicepreferably permits local outflow of bone filler material to thereby forma bone cement layer around at least a portion of the outer porouscontainment device that interdigitates with surrounding bone tissue toanchor the containment device to the surrounding bone tissue, while atthe same time acting a safety barrier for the inner containment device.

Alternatively, the inner containment device may include pores oropenings substantially equal in number and/or diameter to those whichcharacterize the surrounding outer containment device, or may includepores or openings greater in number and/or diameter to those whichcharacterize the surrounding outer containment device. The additionalmaterial thickness as a result of incorporating an outer containmentdevice reduces the likelihood of damage to the containment device duringexpansion.

As previously mentioned, the surface enhancing structures 40 (e.g., theknobs 42, ribs 44 or tentacles 46) can be used in connection with anon-porous containment device. One exemplary method of using one or moresurface enhancing structures with a non-porous containment deviceincludes compacting the interior volume of the targeted vertebral bodyusing a cavity creation device such as, for example, an inflatableballoon. After removal of the cavity creation device, injecting alimited amount of bone filler material into a cannula or into theinterior volume of the targeted vertebral body. Inserting the non-porouscontainment device having one or more surface enhancing structuresformed thereon into the targeted vertebral body. Expanding thenon-porous expandable containment device by, for example, injecting abone filler material into the inner cavity of the non-porous expandablecontainment device so that the textured outer surface of the non-porouscontainment device interdigitates with both the layer of bone cementformed by the initial injection of bone filler material into the cannulaor into the interior volume of the targeted vertebra body, as well asinterdigitates with the surrounding bone tissue. Additional bone fillermaterial may also be injected within the cannula or through the cannuladuring expansion of the non-porous expandable containment device. Thenon-porous expandable containment device may then be removed and thecannula may then be filled with a load bearing system which remainswithin the interior volume to mechanically bear load. The load bearingsystem may be in the form of a non-porous expandable containment devicethat is inflated with a self-hardening bone filler material or any othersystem that can be expandable, cannula filling and load bearing (e.g. anexpandable stent-like structure or a bobbin-like structure around whichis wound biocompatible yarn-like material that forms an expanded loadbearing structure within the cannula). Alternatively, the lastlyinserted load bearing system may simply be a bone filler material thatfills the created cavity. In order to avoid delamination between thelayer of the first bone filler material and the layer of the second bonefiller material, the second bone filler material preferablyinterdigitates with the first bone filler layer via, for example, theopenings formed in the layer of the first bone filling material that wascreated by the textured outer surface such as, for example, via thetentacles, formed on the second expandable container.

As previously mentioned, the bone filler material 50 is preferablyinjected into the inner cavity of the porous containment device 20 viaan injection device 200. The injection device 200 may be any device nowor hereafter known for such purpose. Referring to FIG. 9, one exemplaryembodiment of an injection device 200 will now be described. As shown,the porous containment device 20 (shown in the insertion configuration)may be detachably coupled to a cannulated sleeve 210. The cannulatedsleeve 210 may be coupled to the containment device 20 by any means nowor hereafter known in the art for such purpose including, but notlimited to, a simple mechanical connection. For example the cannulatedsleeve 210 may be coupled to the containment device 20 via a frictionfit, a press-fit or a force fit. In this manner, the cannulated sleeve210 may be coupled to the containment device 20 by pressure and allforces can be transmitted by friction. In use, the containment device 20can be decoupled from the cannulated sleeve 210 by holding thecontainment device 20 in place and pulling the cannulated sleeve 210away from the porous containment device 20. Alternatively, thecannulated sleeve 210 may be coupled to the containment device 20 by athreaded connection, by a bayonet coupling, a plug-in connector such as,by a pin formed in the cannulated sleeve 210 for engaging a slot formedin the containment device 20.

Moreover, the cannulated sleeve 210 may be coupled to the containmentdevice 20 by an intermediary balloon. That is, an intermediary balloonmay be formed on the cannulated sleeve 210 adjacent to a distal endthereof. The cannulated sleeve 210 and the intermediary balloon are theninserted into the containment device 20. Thereafter, inflation of theintermediary balloon causes the balloon to press against the innersurface of the containment device 20 to thereby secure the containmentdevice 20 in place. Alternatively, the cannulated sleeve 210 may becoupled to the containment device 20 via deformation of an elasticelement. That is, the cannulated sleeve 210 may include an innercannulated sleeve and an outer cannulated sleeve wherein the outercannulated sleeve is movably associated with the inner cannulatedsleeve. The elastic element surrounds the inner cannulated sleeve,preferably adjacent to the distal end thereof. The inner cannulatedsleeve and elastic element are inserted into the containment device 20.Thereafter the outer cannulated sleeve is moved relative to the innercannulated sleeve so that the distal end of the outer cannulated sleevecontacts the elastic element. Continued movement of the outer cannulatedsleeve causes the elastic element to deform, resulting in the elasticelement increasing in diameter, which, in turn, causes the elasticelement to press against the inner surface of the containment device 20.Alternatively, the outer cannulated sleeve may be coupled to an elasticcompression ring so that movement of the inner cannulated sleeve withrespect to the outer cannulated sleeve causes the inner cannulatedsleeve to contact and subsequently compress the elastic compressionring, which in turn causes the compression ring to expand and pressagainst the containment device 20.

Moreover, the cannulated sleeve 210 may be coupled to the containmentdevice 20 by a heat sensitive connection. That is, the containmentdevice 20 may be attached to or incorporate a heat sensitive element.Thereafter, as the injected bone cement hardens, the resulting increasein temperature melts the heat sensitive element enabling the containmentdevice 20 to be decoupled from the cannulated sleeve 210.

Furthermore, the cannulated sleeve 210 may be coupled to the containmentdevice 20 by an intermediate clamping element. That is, the cannulatedsleeve 210 may include an inner cannulated sleeve and an outercannulated sleeve wherein the outer cannulated sleeve is movablyassociated with the inner cannulated sleeve. The intermediate clampingelement may be formed on or coupled to the inner cannulated sleeve,preferably on the outer surface of the inner cannulated sleeve adjacentto a distal end thereof. The containment device 20 is thereafter placedbetween the inner cannulated sleeve and the intermediate clampingelement. Thereafter movement of the outer cannulated sleeve with respectto the inner cannulated sleeve causes the outer cannulated sleeve tomove over the intermediate clamping element thus securing thecontainment device.

In addition, the cannulated sleeve 210 may be integrally formed with thecontainment device 20. The integrally formed cannulated sleeve andcontainment device may be separated by a predefined breaking region suchthat during the procedure the containment device 20 be separated fromthe cannulated sleeve 210 by rupturing the breaking region.

Preferably, as shown in FIGS. 10A and 10B, the porous containment device20 may be designed so that it includes a connecting part 300. Theconnecting part 300 may be sized and configured to slidably receive aproximal end 211 of an inner cannulated sleeve 210. Once the connectingpart 300 is slipped over the proximal end 211 of the inner cannulatedsleeve 210, the connecting part 300 can be secured between the outersurface 212 of the inner cannulated sleeve 210 and an inner surface 331of an outer cannulated sleeve 330. That is, the connecting part 300 ofthe containment device 20 may be pinched between the outer surface 212of the inner cannulated sleeve 210 and an inner surface 331 of the outercannulated sleeve 330. Preferably, the outer cannulated sleeve 330 canbe inserted over at least a portion of both the connecting part 300 andthe inner cannulated sleeve 210.

More specifically, the inner cannulated sleeve 210 preferably includes agroove 215 formed adjacent to the proximal end 211 thereof. The groove215 being sized and configured to receive at least a portion of theconnecting part 300. After at least a portion of the connecting part 300is located within the groove 215, the outer cannulated sleeve 330 can bemoved distally with respect to the inner cannulated sleeve 210 so thatat least a portion of the connecting part 300, which is located withinthe groove 215, is sandwiched between the outer surface 212 of the innercannulated sleeve 210 and the inner surface 331 of the outer cannulatedsleeve 330. In use, the diameter of the outer cannulated sleeve 330 ispreferably only a few millimeters bigger than the outer diameter of theinner cannulated sleeve 210. More preferably, the difference indiameters between the outer cannulated sleeve 330 and the innercannulated sleeve 210 is less than the thickness of the porouscontainment device 20. Alternatively, the containment device 20 may beformed with a thicker proximal end so that the thicker end can beinserted into the groove 215 formed adjacent to the proximal end 211 ofthe inner cannulated sleeve 210. Thereafter, the outer cannulated sleeve330 can be moved distally with respect to the inner cannulated sleeve210 securing the thicker end in the groove 215 without pinching ordeforming the containment device 20. Moreover, it is envisioned that thethicker end can be manufactured as a separate component and coupled tothe containment device 20. Alternatively, the thicker end can beintegrally formed via, for example, a hot stamp.

Once the porous containment device 20 has been coupled to the cannulatedsleeve 210, the sleeve 210 and porous containment device 20 may beinserted into the targeted vertebral body V via a small hole formed inthe targeted vertebral body V. A guide wire or similar type structure(not shown) may be initially attached to the distal end of the sleeve210 in order to prevent uncontrolled folding of the containment device20 during insertion into the targeted vertebral body V. The guide wireis removed once the containment device 20 is properly positioned. Theposition of the containment device 20 can be monitored on a radiographicimaging system such as, for example, a C-arm, an X-ray, etc. with theassistance of one or more radiolucent markers such as radiopacity ringsor markers 65 previously described. The porous containment device 20 isdetachable from the sleeve 210 once the containment device 20 isexpanded via injection of the bone filler material 50 through thecannulated sleeve 210 so that the porous containment device 20 and theinjected bone filler material 50 remains within the interior volume 2 ofthe targeted vertebral body V. Preferably, the sleeve 210 includes acheck valve to ensure that bone filler material 50 flows only in onedirection through the sleeve 210 and into (but not back out of) theporous containment device 20.

An exemplary surgical method in accordance with one aspect of thepresent invention includes forming a small targeted incision in thepatient's skin. An extra- or trans-pedicular approach is preferablychosen. More preferably, a bipedicular approach is chosen so that twoporous containment devices 20 can be simultaneously expanded within thepatient's vertebral body. A guide wire or Yamshidi needle with a workingcannula 100 is inserted under C-arm control. A tap may be inserted withthe working cannula 100 over the guide wire, if a guide wire is used.The tap is then preferably removed and the working cannula 100 is left.The sleeve 210 and porous containment device 20 are then preferablyinserted into the interior volume 2 of the targeted vertebral body Vtogether with a guiding wire coupled to the distal end of the sleeve210. The guiding wire is removed once the porous containment device 20is properly positioned. Bone filler material 50 is then injected withadequate viscosity into the porous containment device 20 through thesleeve 210. The containment device 20 is expanded and a bone fillerlayer 51 is formed on the outside of the porous containment device 20,the bone filler layer 51 interdigitates with the surrounding bone tissue4 via outflow of the bone filler material 50 through the containmentdevice 20. The targeted vertebral body V is repositioned. Any residualbone filler material 50 remaining within the cannulated sleeve 210 ispreferably pushed into the porous containment device 20 using, forexample, a pusher. The sleeve 210 is decoupled from the porouscontainment device 20 and removed. All remaining instruments are removedand the incision is closed.

Alternatively, rather than simultaneously inserting the sleeve 210 andporous containment device 20 into the interior volume 2 of the targetedvertebral body V. A low viscous bone cement 50 may be initially injectedinto the cannulated sleeve 210. Thereafter, the containment device 20may be inserted into the interior volume 2 of the targeted vertebralbody V through the cannulated sleeve 210. Additional bone cement 50 maythen be injected into the containment device 20 resulting in theexpansion of the containment device 20. The exterior bone cement 50securing the containment device 20 to the surrounding bone tissue 4.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

What is claimed is:
 1. A porous containment device for implantation inan interior volume of a targeted vertebral body, the porous containmentdevice comprising an outer surface defining an interior cavity forreceiving a bone filler material; the porous containment device furtherincluding: an enlarged proximal portion, an enlarged distal portion, anda narrower central portion located between the enlarged proximal anddistal portions, the narrower central portion having a smaller diameterrelative to the enlarged proximal and distal portions; wherein theporous containment device is expandable from an insertion configurationto an expanded configuration via injection of a bone filler materialinto the interior cavity of the porous containment device; and whereinthe porous containment device includes at least one pore positionedbetween a midline of the narrower central portion and walls of theenlarged distal and proximal portions.
 2. The porous containment deviceof claim 1, wherein the porous containment device includes at least oneair or fluid evacuation pore.
 3. The porous containment device of claim2, wherein the at least one air or fluid evacuation pore is located onthe enlarged proximal or distal portions.
 4. The porous containmentdevice of claim 2, wherein the at least one air or fluid evacuation porehas a diameter smaller than the diameter of the at least one porepositioned between the midline of the narrower central portion and thewalls of the enlarged distal and proximal portions.
 5. The porouscontainment device of claim 2, wherein the at least one air or fluidevacuation pore has a diameter of about 1-49 microns.
 6. The porouscontainment device of claim 1, wherein the at least one pore positionedbetween the midline of the narrower central portion and the walls of theenlarged distal and proximal portions has a diameter of about 50-1000microns.
 7. The porous containment device of claim 1, wherein the atleast one pore positioned between the midline of the narrower centralportion and the walls of the enlarged distal and proximal portionsincludes between 1 and 20 pores.
 8. The porous containment device ofclaim 1, wherein the narrower central portion of the porous containmentdevice includes at least one internal constraint to constrain theexpansion of the narrower central portion.
 9. The porous containmentdevice of claim 1, wherein the narrower central portion of the porouscontainment device includes at least one external constraint toconstrain the expansion of the narrower central portion.
 10. The porouscontainment device of claim 1, wherein the narrower central portion ofthe porous containment device includes at least one internal or externalconstraint to constrain the expansion of the narrower central portion,the at least one internal or external constraint is selected from thegroup consisting of wires, radial rings, yarn, and combinations thereof.11. The porous containment device of claim 1, wherein the outer surfaceof the narrower central portion of the porous containment device isconfigured to enable a portion of the bone filler material to flow outof or through the outer surface of the narrower central portion of theporous containment device so that, in situ when in the expandedconfiguration, the bone filler material is directionally secreted into abuffered zone between the enlarged proximal portion and the enlargeddistal portion such that the bone filler material is semi-contained inthe buffered zone, and the secreted bone filler material interdigitateswith bone tissue in the interior volume of the targeted vertebral body.12. The porous containment device of claim 1, wherein the proximalportion has an outer diameter D1, the distal portion has an outerdiameter D2 and the central portion has an outer diameter D3, D3 beingless than D1 and D2, and wherein D3 is between approximately 5% toapproximately 60% of D1 and D2.
 13. The porous containment device ofclaim 1, wherein the porous containment device further includes at leastone surface enhancing structure to improve frictional contact betweenthe porous containment device and the surrounding bone tissue when inthe expanded configuration.
 14. The porous containment device of claim13, wherein the surface enhancing structure is a plurality of knobs orribs formed on the outer surface of the porous containment devicedesigned to direct the secreted bone filler material.
 15. The porouscontainment device of claim 1 further comprising a connecting part sizedand configured to connect with a cannulated sleeve.
 16. A cannulatedsleeve detachably coupled to the porous containment device of claim 1,the cannulated sleeve comprising an inner cannulated sleeve having anouter surface, an outer cannulated sleeve having an inner surface, andhaving a proximal end designed to engage a portion of the porouscontainment device.
 17. A cannulated sleeve detachably coupled to theporous containment device of claim 15, the cannulated sleeve comprisingan inner cannulated sleeve having an outer surface, an outer cannulatedsleeve having an inner surface, and having a proximal end designed toengage the connecting part of the porous containment device.
 18. Thecannulated sleeve of claim 17, wherein the connecting part of the porouscontainment device is sized and configured to slidably receive theproximal end of the inner cannulated sleeve such that the connectingpart is secured between the outer surface of the inner cannulated sleeveand the inner surface of the outer cannulated sleeve.
 19. The cannulatedsleeve of claim 17, wherein the inner cannulated sleeve includes agroove formed adjacent to the proximal end, and the groove is sized andconfigured to receive at least a portion of the connecting part.
 20. Thecannulated sleeve of claim 19, wherein at least a portion of theconnecting part of the porous containment device is located within thegroove such that the connected part is sandwiched between the outersurface of the inner cannulated sleeve and the inner surface of theouter cannulated sleeve.